Unloader



M. KINDT UNLOADER Oct. '11, 1938.

Filed Nov. 22, 1937 FIG.

3 Sheets-Sheet 1 0a. 11, 1938. r M Kmm 2,132,824

UNLOADER Filed Nov. 22, 195'? 5 Sheets-Sheet 2 FIG.3.

M. KlNDT UNLOADER Oct. 11, 1938.

Filed Nov. 22, 1937 3 Sheets-Sheet 3 Patented Oct. 11, 1938 UNITED STATES UNLOADER Mark K indt, Kenosha, Wis, assignor to Martin P. Winther, Waukegan, 111., as trustee Application November 22, 1937, Serial No. 175,884

Claim.

This invention relates to unloaders, and with regard to certain more specific features, to a power unloader for starting apparatus and the like.

Among the several objects of the invention may be noted the provision of means for powercranking an engine to be tested or otherwise used, such cranking being done by means of an electric motor; the provision of automatic clutch means between said motor and the engine so made and arranged that a single manual movement initiates automatic starting by the motor and automatic unloading of the motor, regardless of any indeterminateness of the engine starting time; and the provision of apparatus of the class described .including automatic means for discharging energy from said clutch as it is opened. Other objects will be in part obvious and in part pointed out hereinafter.

The invention accordingly comprises the elements and combinations of elements, features of construction, and arrangements of parts which will be exemplified in the structures hereinafter described, and the scope of the application of which will be indicated in the following claims.

In the accompanying drawings in whichis illustrated one of various possible embodiments of the invention,

Fig. 1 is a plan view of a starting motor and a starting clutch, both being associated with a dynamometer;

Fig. 2 is a front elevation of Fig. 1;

Fig. 3 is an enlarged vertical section taken on line 3-3 of Fig. 1; and,

Fig. 4 is a diagrammatic layout of the various mechanical and electrical features of the invendrive the latter.

tion.

Similar reference characters indicate correspondine, parts throughout the several views of the drawings.

It is common practice to test prime movers by To accomplish the purpose, the engine is coupled to the dynamometer and the former is operated to Under such circumstances, as well as under many others, it is necessary to crank the engine to start it. Many engines under test are new and the time at which they Y will start is more or less indeterminate, at least until all of the proper adjustments are made on various auxiliaries such as ignition equipment, carouretting equipment and the like. This fact has required that the starting apparatus be given very careful attention by someone in charge, in a order that it may be unloaded from the engine and dynamometer when the engine starts. Inasmuch as the time of starting of the engine is more or less indefinite, any manual unloading scheme is unsatisfactory because of the unsatisfactory coordination of the operator. To solve 5 the above problem and analogous ones, the apparatus herein described is used.

The prime mover to be started is indicated diagrammatically by numeral I in Fig. 4. It is connected to a power-absorbing dynamometer 3 by means of a coupling 5.

At numeral 1 is shown an electric clutch which is coupled (preferably directly) to the dynamometer 3. A motor 9 is connected to the clutch 1 by means of a chain drive ii.

The mechanical details of the clutch 1 are shown in Fig. 3. They comprise a shaft 13 extending from the swinging case 31 of the dynamometer 3. The main bearings for the shaft 13 are in the case 31 (see numerals 2 in Fig. 4). This shaft l3 at its outer end is piloted in bearings i5.

Keyed to the shaft 13 is a magnetic clutch plate 2|. This clutch plate has no endwise motion, but in view of the bearings 15, under open clutch conditions, has relative angular movement with respect to a case 11. The case I1 is bolted at 4 to a sprocket IS.

The sprocket l9 includes a hub 23. In the hub 23 is a pocket for holding a peripherally wound coil 25. The hub 23, like the plate 21 is magnetic, so that if the coil 25 be electrically energized, the resulting magnetic field tends to pull the members 2i and 23 together in an endwise direction.

The sprocket I9 with its hub 23 is mounted for endwise motion upon a bearing ring 21 which slides on a hub 23 of a stationary supporting plate 31. The supporting plate 3| has bolted thereto a sleeve 33 which is integral with and mounted upon stationary standards 39. In the sleeve 33 are bearings supporting one end of the swinging dynamometer case 31. The case 31 must be free to swing in order to deliver to a weighing machine the force of the torque .which is electrically transmitted from the main dynamometer shaft 41 to the frame 31.

From the above it will be seen that the hub 29 does not rotate and that the hub 23 and the sprocket l9 and plate 2i rotate only under action 5 of the chain drive 11.

A spring biasing means for the hub 23 is provided by springs 43 which surround stubs 41, the latter being slidable with respect to the hub 23. Suitable sockets are provided in the hub 23 for the springs 43. The studs 41 are riveted to a common ring 49 which is pressed against a suitable end bearing 5| associated with the stationary hub 29.

From the above it is clear that, if the coil 25 be suitably energized, the resulting electromagnetic field around it will cause an attractive effort between. the plate 2| and the hub' 23.

This efiort draws the movable hub 23 over to the left, thus electrically and frictionally coupling the sprocket I9 and the shaft I3. When the coil 25 is de-energized, the springs- 43 reopen the clutch by separating the members 23 from the member 2|.

It should be understood that the chain drive 'I I is of the multi-band, roller chain variety in which one of the sprockets may be shifted laterally for short distances out of the plane of the other without deleterious effect. The shift in the present example is of the order of of an inch.

The wires for energizing the coil 25 are shown at 53 and are carried on the case I1. The respective wires are in electrical association with respective slip rings 55, mounted on the hub 6 of said case II. The bearing I5 allows for this endwise movement of hub 6 in respect to the shaft I3.

Whenever the motor 9 is energized, the sprocket II is turned (through action of the chain drive II) but in the absence of energization of coil 25 the clutch is open and the sprocket does not transfer its motion to the disc 2|. When the coil is energized, the hub 23 is drawn against said disc 2|, and the driving friction between the surfaces of members 2| and 23 causes the rotation of the dynamometer shaft I3. The shaft I3 being coupled to the engine shaft results in cranking of the engine.

Whenever the engine starts, it is desirable that the field circuit of coil 25 be broken in order that the driving connection between members 2| and 23 may be broken. This is to permit the engine to drive the shaft I3 without transmitting motion to the motor 9, thus unloading the motor from the engine.

The brushes for energizing the field circuit and associated with the slip rings 55 are shown at 51 in Figs. 1 and 2. These brushes are mounted upon a bracket 59 which in turn is carried upon a guard '6I extending from the stationary plate 3|.

- The electrical circuit (Fig. 4) comprises a preferably three-phase, alternating-current power circuit 63, in one phase-wire of which is a coil At numeral 69 is shown a motor-starting switch and at numeral 1| a reversing switch. The circuit 63 is connected with the motor 9 through these switches. The switch 59 is normally held open by the spring II. The switch carries a movable armature I3 which is associated with a coil 15.-

, At numeral 11 is shown a direct-current supply circuit energized from a suitable battery or the like which includes a lead 19 passing through the coil 25 of the electrical clutch I. The lead ,19 passes, by way of contacts 8| and lead 14, to the coil 15. The circuit is completed by leads 103, 8 9,--, 9I,and switches 95 and 91 across con- 91. The switch 95 is normally'drawn open by a spring 99 and carries a movable armature IOI. Armature |I maybe drawn to the left by a coil I 03. The coil I03 is connected across the circuit 11 by way of leads I9 (passing through the coil 25) and 9|.

Switch 91 carries a movable armature I associated with a coil I01, the latter being in a field-discharge, relay circuit comprising leads I09, contactsIII, armature II3, contacts 5 (normally closed by a switch H1) and lead H9.

The switch 9! is moved to close the contacts 93 when the coil I01 is energized and is gravitationally moved to open said contacts when the coil I01 is de-energized. When the contacts 93 are opened, contacts |2| are closed. These contacts |2| are in a field-discharge circuit comprising lead I23, resistance I and lead I21.

The armature H3 and one of the contacts III are normally drawn down by a spring |2 9 but may be pushed up by pressure on a springreturned starting button I3I. The switch 1 normally closes the contacts II5 but may be pushed open in an emergency by means of an emergency button I33.

The operation of the apparatus is as follows:

Assuming-that supply circuits 63 and 11 are energized and that the engine I is stationary and connected to the dynamometer 3, the starting button I 3| is then temporarily pressed. This forces the armature I|3 into close proximity to the core 61 of energized coil 65 and closes the contacts III.

As soon as the contacts III close, the following field-discharge relay circuit is closed: I09, I01, III, H3, H5, H1, H9. This circuit is energized from the direct-current circuit 11 and results in the coil I05 being lifted to close contacts 93. With the contacts 93 closed, the following circuit is energized: 9|, 93, 96, I03, I9, and field coil 25. This has the effect of drawing over the armature IOI of coil I03. to close the switch 95, thereby energizing the coil I5 in the circuit 14, 15, 83, 89. This draws down the core 13 to close the motor starting switch 69.

It is desirable that the coil I03 close the contacts 8| after the current in coil 25 has reached a value adapted'to have closed the clutch. Thus the coil I03 and spring 99 are designed so that, not until the current in the coil 25 rises to about '15 percent of the maximum value, will the flux in coil I03 be sufi'icient to start closing the contacts 8|. By this means a time-delay action is obtained between the energization of clutch coil 25 and the actual closing of the main switch 69. Thus the clutch members 23 and 2| are pulled together (closed), before any torque is applied to the clutch by the motor 9.

If-the function were otherwise, it would be necessary to provide wearing material between the clutch members 23 and 2|. Such interposed material would necessitate the use of substantially more magnetomotive force in the coil 25, because of the necessarily increased flux gap during operating conditions. By first closing the clutch, before relative angular motion exists between members 23 and 2 I, the necessity for these disadvantageous wearing surfaces is eliminated. Furthermore, substantially no wear will occur at the friction surfaces between clutch members 23 and- 2|, because static friction only is relied upon for transmitting torque, rather than upon any sliding friction.

Under the above conditions, when the motor 9 is drawing a heavy starting current. in circuit I53, coil has a great magnetizing effect upon the core -61, thus holding the armature H3 in place, even though the starting button IlI should be released. For example, an inrush currentof 140 amperes may be expected over the circuit 63 in certain applications of the invention.

After the clutch 1 has closed and the motor 9 is running and driving the engine I through the clutch 1 and dynamometer 3, the current will drop, but not enough to efiect release of the armature II3. For instance, on the above assumed 140 ampere basis, a running current of 26 amperes may be expected. This running current is enough to cause the armature Ill to hold the switch II I shut, the coil 65 having been wound for the purpose.

Thus, the motor 9 will continue to drive the engine I until the latter starts to operate, and

.as above shown, this may require an indefinite period. However, the operator of button I3I is free to go about other duties.

Finally, when the motor I does start to operate, it is temporarily eifective to drive the motor 9 through the chain drive II. This reduces the motor current, because the back-electromotiveforce is increased in circuit 63. This reduces the current in the coil 65. For example,the current under running conditions of the engine I may be of the order of amperes (on the 140 ampere and 26 ampere basis above given). .Un der these conditions, the armature I I9 is adapted to be drawn back by the spring I29, thus breaking the circuit through coil I01. This allows the switch 91 to drop away from the contacts 99 and hence to de-energize coil I03. This breaks the circuit through the electric clutch coil 25, and at the same time the circuit through coil is broken by opening of the switch 95. Under these conditions, the clutch opens, causing drive II to be mechanically disconnected from shaft I3, and

the motor 9 is unloaded and de-energized. The only load upon the prime mover I is that of the dynamometer 3. It will be noted that the driving torque of motor 9 is nullified by opening of the switch 69 before the clutch opens.

The circuit is then again in the condition shown in Fig. 4, the switch 91 having dropped back to close contact across the contacts I2I. This closes the circuit through 19, I03, 96, 89, I23, I2I, 91, resistance I25 and lead I21. This circuit is across the coil 25 and has for its purpose, when closed as described, to function as a field discharge circuit for the coil 25 when the magnetic field around the coil collapses to induce current flow therein. The discharge is dissipated as heat in the resistance I25.

The purpose of the emergency switch H1 and button Hills to permit of opening the circuit which energizes coll I01 at any time after starta ing of the engine hasv been attempted; as for instance, when the prime mover cannot be adjusted to effect a start under its own power after having run. for a period. Under emergency stop conditions, the de-energization of the coil I01 causes the contacts 93 to open while contacts I2I c ose, thus establishing the field dis charge circuit and causing the switch 95 to open and resulting in the de-energization of co l 15 with resultant opening of the main switch 69. Under these conditions the clutch also is opened after the switch 69 opens.

As soon as the current in themain circuit 63 becomes zero, thus de-energizing the coil 65 and releasing armature N3, the button I33 may be released with the assurance that the circuit will remain in the condition shown in Fig. 4 until the starting button I3I is again pressed.

It is to be understood that the engine, when starting temporarily, drives the motor 9 in the same direction that the motor 9 runs to drive the engine. The purpose of the reversing switch 1| is to permit this condition for starting various engines that operate in opposite directions.

Stated otherwise, the switch H is to permit the motor 9 to be operated in either direction, thus providing means for turning over any prime mover I in either possible direction.

While the term, field-discharge relay circuit, has been applied to the specific circuit which energizes and de-energizes coil I01, it is to be understood that the three circuits which energize (1) coil I01, (2) coil.l09 (when the'contacts 99 are closed by switch 91), and (3) coil 15, constitute relay means by which the switch 69 is closed from the starting button I3I or reopened either by automatic opening of contacts III or by emergency manual opening of contacts II5.

In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained.

As many changes could be made in carrying out the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description .or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

I claim:

1. Starting apparatus for prime movers and said circuit means being adapted to be automatically reopened by release of the holding means in response to a predetermined relatively low current in the motor circuit as when the prime mover starts, whereby the motor circuit is opened and said clutch is de-energized and opened, and means for automatically electrically discharging said clutch when said circuit means is reopened.-

2. Apparatus for starting prime movers and the like comprising an electric clutch having a coil for closing purposes, a driving motor mechanically connected with said clutch, a motor circuit for said motor, a circuit for said coil, manual closing means for closing said coil circult and said motor circuit whereby the clutch is closed and said prime mover started, said manually operable means being adapted to be held in circuit-closing position under conditions of starting and running current in said motor circuit but adapted automatically to open under the current conditions prevailing in said circuit when the prime mover starts and incipiently drives the motor, and a field discharge circuit adapted to be closed when said circuit-closing means reopens.

3. Apparatus for starting prime movers and the like comprising a starting motor, an electric clutch connected between said starting motor and said prime mover, a field coil in said clutch, a motor circuit, a main switch in said motor circuit, a field coil circuit, a main-switch-operating circuit, a relay for closing said field coil circult, a circuit for said relay adapted to be manually closed a relay for the main switch,

- said main switch being operable to close the motor circuit when said field coil circuit is closed. and means energized by the motor circuit adapted in response'to current values in the motor circuit corresponding to the requirements for starting and driving said prime mover to maintain the relay switch circuit closed after closure thereof, but adapted to permit reopening of said relay circuit under current conditions corresponding to conditions after starting of the prime mover.

4. Apparatus for starting prime movers and the like comprising a starting motor, an electric clutch connected between said starting motor and said prime mover, a field coil in said clutch, a motor circuit, a main switch in said motor circuit, a field coil'circuit, a main-switch-operating circuit, a relay for closing said field coil circuit, a circuit for said relay adapted to be manually closed, a relay for the main switch, said main switch being operable to close the motor circuit when said field coil circuit is closed, and means energized by the motor circuit adapted, in response to current values in the motor circuit corresponding to the requirements for starting and driving said prime mover, to maintain the relay switch circuit closed after manual closure thereof, but adapted to permit reopening of said relay circuit under current conditions corresponding to running conditions of said prime mover, and a field discharge circuit adapted to be closed whenever said field coil circuit is open, said field discharge circuit having energy-dissipating means therein.

5. Apparatus for starting prime movers. and the like comprising a starting motor, an electric clutch connected between said starting motor and said prime mover, a field coil in said clutch adapted to close the clutch when energized, a motor circuit, .a main. switch in said motor circuit, a field-coil circuit, a main switch circuit, a relay for closing said field-coil circuit, a circuit for said relay adapted to be manually closed, a relay in the field-coil circuit whereby the main switch circuit is closed when said field-coil circuit is closed, and means energized by the motor circuit adapted to maintain the manually-closed circuit closed in response to current values in the motor circuit corresponding to the requirements for starting and driving said prime mover, but adapted to permit reopening of said manually-closed circuit under current conditions corresponding to running conditions of said prime mover, and a field-discharge circuit adapted to be closed whenever said fleld-coil'circuit is opened, said field-discharge circuit having energy-dissipating means therein, and an emergency stop means in said circuit for the relay adapted to break the relay circuit to open said main switch and said field-coil circuit.

6. Starting apparatus for prime movers comprisinga clutch associated with the prime mover, an electric motor for driving the clutch, an energizing circuit for said motor, a main switch in said energizing circuit, returnable manually movable means, circuit means between said manually movable means and said main switch adapted to be closed by manual movement oi said movable means and to close the main switch, means between said main circuit and said manually movable means whereby any current in said energizing circuit above -a predetermined value is adapted to hold said manually movable means in its manually moved position and wherein said circuit means holds said main switch closed, "and whereby any current below said predetermined value permits return action of said manually movable means, the return action or said manually movable means conditioning said circuit means to eiiect opening of the main switch.

'7. Starting apparatus for prime movers comprising an electric clutch associated with the prime mover, an electrici notor for driving the clutch, an energizing circuit for said motor, a normally open main switch in said energizing circuit, returnable manually movable means, relay circuit means between said manually movable means and said main switch adapted upon manual movement of said movable means to close the main switch, "means between said main circuitand said manually movable means whereby any current in said energizing circuit above a predetermined value is adapted to hold said manually movable means in its moved position wherein said relay means holds said main switch closed, and whereby any current below said predetermined value permits return action of said manually movable means, the return action of said manually movable means conditioning the relay circuit to release the main switch to open, and means whereby said relay circuit energizes the clutch to close whenever the main switch closes and vice versa.

8. Starting apparatus for prime movers comprising a clutch associated with the prime mover, an electric motor for driving the clutch, an energizing circuit for said motor, a switch in said energizing circuit, manually movable means, circuit means between said manually movable means and said main switch adapted to be closed by manual movement of said movable means and to close the main switch, a clutch operating coil in said circuit means, a relay in said circuit means, said relay being adapted to permit building-up of clutch-closing current in said relay before closure of said main switch.

9. Starting apparatus for prime movers comprising a clutch associated with the prime mover, an electric motor fordriving the clutch, an energizing circuit for said motor, a switch in said energizing circuit, returnable manually movable means, circuit means between said manually movable means and said main switch adapted to r be closed by manual movement of said movable means and to close the main switch, a clutch operating coil in said circuit means, a relay in said circuit means, said relay being adapted to permit building-up of clutch-closing current in said I relay before closure of said main switch, means.

between said main circuit and said manually movable means whereby any current in said onergizing circuit above 'a predetermined value is adapted to hold said manually movable means in its manually moved position and wherein said be closed'by manual movement of said movable means and to close the main switch, a clutch operating coil in said circuit means, a relay in said circuit means, said relay being adapted to permit building-up of clutch-closing current in said relay before closure of said main switch, means between said main circuit and said manually movable means whereby any current in said energizing circuit above a predetermined value is adapted to hold said manually movable means in its manually moved position and wherein said circuit means holds said main switch closed, and whereby any current below said predetermined value permits return action of said manually movable means, the return action of said manually movable means conditioning said circuit means to effect opening of the main switch,- the main switch opening before the clutch coil is de-energized enough to permit clutch opening.

11. Starting apparatus for prime movers and g the like comprising a magnetic clutch associated with the prime mover, a field coil for closing the clutch, an electric motor for driving the clutch, and means operative by a single movement to energize first the coil to a degree to close the clutch and then the motor to start said motor when the clutch is closed.

12. Starting apparatus for prime movers and the like comprising a magnetic clutch, a driving element and a driven element in the clutch, said driven element being associated with the prime mover, a motor articulated to the driving element, a field coil associated with said driving and driven elements of the clutch so as to'magnetically link them, said driving and driven elements having frictional engaging surfaces and being composed of magnetic material at said surfaces, circuit means for energizing the clutch to mflimetically link them, said driving and driven elements having frictional engaging surfaces and being composed of magnetic material at said surfaces, a circuit for energizing the clutch, a separate circuit for energizing the motor, a switch in the motor circuit, and relay means between the field coil circuit and the motor switch whereby, when the field coil circuit is substantially energized to efl'ect clutch closure, said motor switch is thereafter closed to start the motor.

14. Starting apparatus for prime movers and the like comprising a magnetic clutch, a driving element and a driven element in the. clutch, said driven element being associated with the prime mover or the like, a motor articulated to the driving element, a field coil associated with said driving and driven elements of the clutch so as to magnetically link them, said driving and driven elements having frictional engaging surfaces and being composed of magnetic material at said surfaces, a circuit for energizing the clutch, a separate circuit for energizing the motor, a switch in the motor circuit, and relay means between the field coil circuit and the motor switch whereby, when the field coil circuit is substantially energized to effect clutch closure, said motor switch is thereafter closed, and means responsive to conditions of current in the motor circuit adapted to hold said field coil circuit in closed condition until the current in the motor circuit drops below a value predetermined by starting of the prime mover.

15. Starting apparatus for prime movers and the like comprising a magnetic clutch, a driving element and a driven element in the clutch, said driven element being associated with the prime mover or the like, a motor articulated to the driving element, a field coil associated with said driving and driven elements of the clutch so as to magnetically link them, said driving and driven elements having frictional engaging surfaces and being composed of magnetic material at said surfaces, a circuit for energizing the clutch, a separate circuit for energizing the motor, a switch in the motor circuit, and relay means between the field coil circuit and the motor switch whereby, when the field coil circuit is substantially energized to effect clutch closure, said motor switch is thereafter closed, means responsive to conditions of current in the motor circuit adapted to hold said field coil circuit in closed condition until the current in the motor circuit drops below a value predetermined by starting of the prime mover, and field discharge means automatically operative upon opening of the field coil circuit.

' MARK min. 

